Packets and information regarding the packets may be generated by a traffic routing device, such as a router, a switch, etc. External tapping devices, such as TAPs, may tap into a network to obtain packets that are copies of the packets from the network. However, external tapping devices may not be able to obtain some information that only the traffic routing device knows. For example, the input interface at which the packet arrives, and/or the output interface from which the packet departs, is unknown to the external tapping device and cannot be determined by the external tapping device. The external monitor has no way of identifying that a particular packet arrived from a particular interface of the routing switching device.